Observation of Binding and Rotation of Methane and Hydrogen within a Functional Metal–Organic Framework

[Image: see text] The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH(4)) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH(4) and 488 v/v at 77 K and 20 bar for H(2). Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH(4) and H(2) molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H(2) and CH(4) molecules within MFM-300(In), reminiscent of the condensed gas in pure component crystalline solids. We also report here, for the first time, the experimental observation of a direct binding interaction between adsorbed CH(4) molecules and the hydroxyl groups within the pore of a material. This is different from the arrangement found in CH(4)/water clathrates, the CH(4) store of nature.